Solder bump, electronic component and method for manufacturing the electronic component

ABSTRACT

An electronic component includes a plurality of first electrode pads arranged on a first substrate, a plurality of second electrode pads arranged at positions corresponding to the first electrode pads on a second substrate and a plurality of solder bumps which join together the first electrode pads and the second electrode pads. Here, the first substrate is located over the second substrate so that the first electrode pads and the second electrode pads are at positions which are shifted from opposite positions where the first electrode pads opposite to the second electrode pads, and at least a part of the solder bumps are solidified into hourglass-shaped.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. JP 2008-065926, filed on Mar. 14, 2008,the disclosure of which is incorporated herein in its entirety byreference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a plurality of solder bumps each ofwhich joins electrodes together, an electronic component including theplurality of solder bumps and a method for manufacturing the electroniccomponent. In particular, the present invention relates to an electroniccomponent in which a chip or the like is installed by using of flip chipor BGA (Ball Grid Array), and a method for manufacturing the electroniccomponent.

2. Background Art

As an electronic component, there is a semiconductor component includinga substrate on which an LSI chip is mounted. FIG. 13A is a plan view ofa general semiconductor component and FIG. 13B is a side view of thegeneral semiconductor component. In FIG. 13A and FIG. 13B, asemiconductor component 100 has a structure that an LSI (Large ScaleIntegrated circuit) chip 102 having a plurality of electrode pads 101 ismounted over a resin substrate 104 having a plurality of electrode pads103. In FIG. 13B, each of the electrode pads 101 and each of theelectrode pads 103 are joined together via one of solder bumps 105.

When the LSI chip 102 or an apparatus including the semiconductorcomponent 100 is heated, the LSI chip 102 and the resin substrate 104expand. Since linear expansion coefficient of the resin substrate 104 isgenerally smaller than that of the LSI chip 102, thermal stress isgenerated at a joining area of the solder bump 105. Then, exfoliation ofthe joining area and destruction of the solder bump 105 occur in somecases.

A related art 1 (Japanese Patent Application Laid-Open No. 1998-223693)and a related art 2 (Japanese Patent Application Laid-Open No.2005-340674) disclose a technology which suppresses exfoliation of thejoining area and destruction of the solder bump due to the thermalstress.

The related art 1 discloses a technology that an LSI chip is arrangedover a resin substrate, and the LSI chip is lifted from the resinsubstrate during a heating process. When the LSI chip is lifted whilesolder bumps are melting, the solder bumps are stretched and become intohourglass-shaped. Here, a contact angle between a peripheral surface ofa solder bump and an electrode pad at the joining area (hereinafter,referred simply to as contact angle of joining area) of thehourglass-shaped solder bump is smaller than that of an usual solderbump. When the contact angle of joining area becomes small, the thermalstress which is applied to the joining area is reduced. Accordingly, itis possible to suppress exfoliation of the joining area and destructionof the solder bump.

Meanwhile, the related art 2 discloses a technology that four electrodepads of a LSI chip which are the nearest to corners of the LSI chip arearranged at positions which come off from a aligning position of otherson the LSI chip, and all of electrode pads of a resin substrate arearranged at aligning positions on the resin substrate. Accordingly, foursolder bumps which are the nearest to corners of an LSI chip slanttoward nearby one of the four electrode pads of the LSI chip andsolidify into hourglass-shape. When the LSI chip expands larger than theresin substrate during a heating process, the hourglass-shape solderbumps become into upright state. Accordingly, it is possible to suppressexfoliation of the joining area and destruction of the solder bump.

SUMMARY

An exemplary object of the present invention is to provide a solderbump, an electronic component and a method for manufacturing theelectronic component, which can suppress exfoliation of a joining areaand destruction of the solder bump due to a thermal stress. Moreover,another exemplary object of the present invention is to provide a solderbump which joins together electrode pads, an electronic componentincluding the solder bumps and a method for manufacturing the electroniccomponent, which require neither a complicate process for manufacturingelectrode pads nor a precise lifting apparatus.

A plurality of solder bumps according for an exemplary object of theinvention join together first electrode pads and second electrode padsat positions which are shifted from opposite positions where the firstelectrode pads opposite to the second electrode pads. Here, at least apart of the solder bumps are solidified into hourglass-shaped.

An electronic component according for an exemplary object of theinvention includes a plurality of first electrode pads arranged on afirst substrate, a plurality of second electrode pads arranged atpositions corresponding to the first electrode pads on a secondsubstrate and a plurality of solder bumps which join together the firstelectrode pads and the second electrode pads. Here, the first substrateis located over the second substrate so that the first electrode padsand the second electrode pads are at positions which are shifted fromopposite positions where the first electrode pads opposite to the secondelectrode pads, and at least a part of the solder bumps are solidifiedinto hourglass-shaped.

A method for manufacturing an electronic component according for anexemplary object of the invention includes arranging a plurality offirst electrode pads and a plurality of second electrode pads on a firstsubstrate and a second substrate respectively so that positions of thesecond electrode pads correspond to those of the first electrode pads,forming a plurality of solder bumps on the second electrode padsrespectively, putting the first substrate over the second substrate sothat the first electrode pads are respectively opposed to the secondelectrode pads via the solder bumps, shifting the first substrate orsaid second substrate in parallel to the second substrate while thesolder bumps are melting so that the solder bumps are stretched in aslant direction to cause the solder bumps to be solidified intohourglass-shaped.

A method for manufacturing an electronic component according for anexemplary object of the invention includes arranging a plurality offirst electrode pads and a plurality of second electrode pads on a firstsubstrate and a second substrate respectively so that positions of thesecond electrode pads correspond to those of the first electrode pads,forming a plurality of solder bumps on the second electrode padsrespectively, putting the first substrate over the second substrate viathe solder bumps so that each of the first electrode pads and each ofthe second electrode pads are at positions which are shifted from theiropposite positions to cause the solder bumps to be solidified intohourglass-shaped by heating.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary features and advantages of the present invention will becomeapparent from the following detailed description when taken with theaccompanying drawings in which:

FIG. 1 is a side view of a solder bump of a first exemplary embodimentaccording to the present invention;

FIG. 2A is a plan view of an electronic component of a second exemplaryembodiment;

FIG. 2B is a transverse cross-sectional view of the electronic componentof the second exemplary embodiment;

FIG. 3A is a plan view showing a method for manufacturing the electroniccomponent of the second exemplary embodiment;

FIG. 3B is a transverse cross-sectional view showing the method formanufacturing the electronic component of the second exemplaryembodiment;

FIG. 4A is a plan view showing the method for manufacturing theelectronic component of the second exemplary embodiment;

FIG. 4B is a transverse cross-sectional view showing the method formanufacturing the electronic component of the second exemplaryembodiment;

FIG. 5A is a plan view showing the method for manufacturing theelectronic component of the second exemplary embodiment;

FIG. 5B is a transverse cross-sectional view showing the method formanufacturing the electronic component of the second exemplaryembodiment;

FIG. 6 is a perspective view showing a simulation result on thermalstress of a solder bump in the second exemplary embodiment;

FIG. 7 is a perspective view showing a simulation result on thermalstress of a solder bump of an example to be compared;

FIG. 8 is a perspective view showing a simulation result on thermalstress of a solder bump of an example to be compared;

FIG. 9A is a top view of a resin substrate 14 in a third exemplaryembodiment;

FIG. 9B is a perspective view of a top surface of an LSI chip 12 in thethird exemplary embodiment;

FIG. 10A is a plan view showing a method for manufacturing an electroniccomponent of the third exemplary embodiment;

FIG. 10B is a plan view showing the method of manufacturing theelectronic component of the third exemplary embodiment;

FIG. 10C is a transverse cross-sectional view of the electroniccomponent of the third exemplary embodiment;

FIG. 11A is a plan view showing a method of manufacturing an electroniccomponent of a fourth exemplary embodiment;

FIG. 11B is a transverse cross-sectional view of the electroniccomponent of the fourth exemplary embodiment;

FIG. 12A is a plan view of an electronic component of a fifth exemplaryembodiment;

FIG. 12B is a transverse cross-sectional view of the electroniccomponent of the fifth exemplary embodiment;

FIG. 13A is a plan view of a general semiconductor component; and

FIG. 13B is a side view of the general semiconductor component.

EXEMPLARY EMBODIMENT

Exemplary embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

First Exemplary Embodiment

A solder bump of a first exemplary embodiment according to the presentinvention will be described with FIG. 1. In FIG. 1, two of firstelectrode pads 3 and two of second electrode pads 5 are arranged on afirst substrate 2 and a second substrate 4 respectively so that they areat positions which are shifted parallel to the second substrate 4 fromopposite positions where the first electrode pads 3 opposite to thesecond electrode pads 5. Here, at least a part of plural solder bumps 1each of which joins one of the first electrode pads 3 and one of thesecond electrode pads 5 are solidified into hourglass-shaped. In FIG. 1,two solder bumps 1 are hourglass-shaped.

The solder bumps 1 shown in FIG. 1 can be manufactured, for example, asdescribed in the following. That is, creamy solder is supplied on eachof the second electrode pads 5 which are formed on the second substrate4 with the screen printing technology. Then, the first substrate 2 isput over the second substrate 4 so that the first electrode pads 3 areopposed to the second electrode pads 5 each other via the solder and thesolders start to be heated in this state. Then, the first substrate 2and the second substrate 4 are relatively shifted in horizontaldirection while the solders are melting, and the solders are stretchedin a slant direction because the first electrode pads 3 and the secondelectrode pads 5 are shifted. Moreover, the solders are cooled in thisshifted state and are solidified into hourglass-shaped as solder bumps1.

Here, a contact angle of joining area of the hourglass-shaped solderbump 1 is smaller than that of usual solder bump. Accordingly, stresswhich is applied to the joining area of the hourglass-shaped solder bump1 is reduced and it is consequently possible to suppress exfoliation ofthe joining area and destruction of the bump 1. Moreover, a preciselifting apparatus is unnecessary on manufacturing the hourglass-shapedsolder bump 1 of this embodiment of the present invention.

Here, the smaller the contact angle of joining area of the solder bump 1becomes, the less stress which is applied to the solder bump 1 becomes,that is, the larger an amount of deformation of the solder bump 1 byshifting becomes, the less stress becomes. However, when an amount ofdeformation of the solder bump 1 is too large, a possibility that thesolder bump 1 is torn off becomes high. So, it is desirable that ashifting length between the first substrate 2 and the second substrate 4is set to be shorter than diameters each of the electrode pad 11 and theelectrode pad 13. In this embodiment, the shifting length is set to benearly as long as a diameter each of the first electrode pad 3 and thesecond electrode pad 5. Accordingly, it is possible to maximally reducethe stress which is applied to the joining area of the solder bump 1 ina range where the solder bump 1 is not torn off.

Second Exemplary Embodiment

An electronic component of a second exemplary embodiment according tothe present invention will be described with FIG. 2A and FIG. 2B. FIG.2A is a plan view of an electronic component 10 of this embodiment. FIG.2B is a transverse cross-sectional view which is taken along a line X-X′of the electronic component 10 shown in FIG. 2A. In FIG. 2A and FIG. 2B,the electronic component 10 includes an LSI chip 12 which has aplurality of electrode pads 11, a resin substrate 14 which has aplurality of electrode pads 13, and a plurality of solder bumps 15 eachof which joins one of the electrode pads 11 and one of the electrodepads 13. Here, the LSI chip 12 is corresponding to the first substrateand the resin substrate 14 is corresponding to the second substrate.Moreover, the electrode pad 11 is corresponding to the first electrodepad and the electrode pad 13 is corresponding to the second electrodepad.

In FIG. 2A, a plurality of electrode pads 11 is formed on the LSI chip12 in an aligned state, and a plurality of electrode pads 13 is formedon the resin substrate 14 so that positions of electrode pads 13correspond to those of the electrode pads 11 of the LSI chip 12 eachother.

The LSI chip 12 is made of, for example, silicon and the resin substrate14 is made of general synthetic resin. The electrode pad 11 and theelectrode pad 13 are made of conductive metal such as copper. Surfacesof the electrode pad 11 and the electrode pad 13 are coated with a filmwhich has solder wettability and which is made of, for example, gold orsolder alloy. The solder bump 15 is made of general lead-free solder.

In FIG. 2A, the electrode pads 11 are not opposed to the electrode pads13 completely. Each of the electrode pads 11 and each of the electrodepads 13 are at positions which rotate centering on “O” shown in FIG. 2Afrom their opposite positions. Here, the center O is a center of the LSIchip 12 or the resin substrate 14. In FIG. 2A and FIG. 2B, the electrodepad 11 and the electrode pad 13 are described more exaggeratedly thanother part in order to make it easy to understand.

Next, a method for manufacturing the electronic component 10 of thisembodiment will be described with FIG. 3A to FIG. 5B. FIG. 3A, FIG. 4Aand FIG. 5A are plan views of the electronic component 10 in each ofmanufacturing processes. FIG. 3B, FIG. 4B and FIG. 5B are transversecross-sectional view of the electronic component 10 in each ofmanufacturing processes.

In FIG. 3A, the LSI chip 12 and the resin substrate 14 are formed in ashape of square. A plurality of electrode pads 13 are arranged on amounting surface of the resin substrate 14 in an aligned state, and aplural of electrode pads 11 are arranged on a mounting surface of LSIchip 12 so that positions of electrode pads 11 correspond to those ofthe electrode pads 13.

When the electronic component 10 is manufactured with theabove-mentioned resin substrate 14 and the LSI chip 12, at first, creamysolder is supplied on each of the electrode pads 13 of the resinsubstrate 14 with the screen printing technique and the solder bumps 15are formed. The LSI chip 12 is put over the resin substrate 14 so thatthe electrode pads 11 are opposed to the electrode pads 13 respectivelyvia the solder bumps 15 respectively.

Next, as shown in FIG. 4A and FIG. 4B, a vacuum suction tool 17 is seton a top surface of the LSI chip 12 so that the center of the vacuumsuction tool 17 corresponds to the center of the LSI chip 12. Then, theLSI chip 12 and the resin substrate 14 start to be heated in this state.

While the solder bumps 15 are melting, the LSI chip 12 rotates the angleθ in parallel to the resin substrate 14 centering on “O” with the vacuumsuction tool 17 as shown in FIG. 5A. Then, the solder bumps 15 arestretched in a slant direction as shown in FIG. 5B. The solder bumps 15are cooled in this state and are solidified, so the electronic component10 including the hourglass-shaped solder bumps 15 is manufactured.

In the above-mentioned manufacturing method of the electronic component10, a precise lifting apparatus is unnecessary. The electrode pads 11and the electrode pads 13 can be formed with the same method sincepositions of the electrode pads 13 correspond to those of the electrodepads 11. Accordingly, a complicate process for manufacturing theelectrode pad is unnecessary.

Moreover, in the electronic component 10, the contact angle of joiningarea of the hourglass-shaped solder bump 15 is smaller than that of anusual solder bump. Accordingly, stress which is applied to the joiningarea is reduced and it is consequently possible to suppress exfoliationof the joining area and destruction of the solder bumps 15.

Here, since surface area of the resin substrate 14 is larger than thatof the LSI chip 12, the LSI chip 12 rotates centering on “O” which is acenter of the resin substrate 14. The larger a distance from the “O” tothe solder bump 15 is, the longer a shifting length between theelectrode pads 11 and the electrode pads 13 which are joined by thesolder bump 15 is, that is, the bigger an amount of deformation of thesolder bump 15 becomes. On the other hand, in general, the stress whichis applied to the joining area of the solder bump 15 grows in proportionto the distance from the center of a substrate. Accordingly, in thisembodiment, it is possible for the electronic component 10 to reduceeffectively the stress on the basis of the stress distribution.

However, when the shifting length between the electrode pads 11 and theelectrode pads 13 is too large, a possibility that the solder bump 15 istorn off becomes high. It is desirable that the shifting length betweenthe electrode pads 11 and the electrode pads 13 which are arranged atthe farthest position from the center O is shorter than a diameter eachof the electrode pad 11 and the electrode pad 13. Then, the rotationangle θ is expressed as

θ=tan−1 (d/r)

where r is a distance from the center O to one of the solder bumps 15which is farthest from the center O, and d is a diameter of theelectrode pads 11 and the electrode pads 13. In this case, it ispossible to maximally reduce the stress which is applied to the joiningarea of the solder bump 15 in a range where the solder bumps 15 are nottorn off.

Here, in this embodiment, while the electrode pads 11 and 13 arearranged in a form of array type as shown in FIG. 2A, these may bearranged in a form of peripheral type. While number of the electrodepads 11 and the electrode pads 13 are “36” respectively, the number isnot limited to “36”. Furthermore, while a two-layered structureincluding the LSI chip 12 and the resin substrate 14 is applied to theelectronic component 10, a structure of multiple layers including morethan three layers may be applied.

Instead of the LSI chip 12A, substrate or the like on which othersemiconductor chips or many electronic components are mounted can beapplied as the first substrate. Instead of the resin substrate 14, aceramics substrate, a glass substrate or a semiconductor chip can beapplied as the second substrate. Furthermore, shape of top surface ofthe LSI chip 12 and the resin substrate 14 is not limited to a square,but it may be formed to, for example, a polygon, a circle or an ellipse.

Next, a simulation result on thermal stresses of solder bumps will bedescribed. FIG. 6 shows a simulation result of thermal stresses appliedto the solder bumps 15 of the electronic component 10 of thisembodiment. FIG. 7 shows a simulation result of thermal stresses appliedto solder bumps of an usual electronic component. FIG. 8 shows asimulation result of thermal stresses applied to solder bumps of anelectronic component all of whose solder bumps are formed tohourglass-shaped.

All of them are the simulation results under that an electroniccomponent including an LSI chip and a resin substrate which are joinedtogether by the solder bumps whose number is “12” times “12”, that is,“144”, is heated. In FIG. 6 to FIG. 8, stress values which are appliedto solder bumps arranged at four corners are indicated near the solderbump in the figure respectively. The stress values are largest since thesolder bumps arranged at the four corners are farthest from center ofthe LSI chip. Here, a scale coefficient in FIG. 6 to FIG. 8 meansmagnification for expressing an amount of deformation of the solder bumpmore exaggeratedly than actual deformation. In FIG. 6 to FIG. 8, thescale coefficients are set so that maximum amount of deformation of thesolder bump may be corresponding to 10% of the longest length of theanalysis model.

In FIG. 6, the maximum stress value of the solder bump is 2384 [MPa] ofthe electronic component 10 of this embodiment. In FIG. 7, it is 3186[MPa] of the usual electronic component. In FIG. 8, it is 1657 [MPa] ofthe electronic component all of whose solder bumps are formed tohourglass-shaped. According, the electronic component 10 of thisembodiment can reduce by 25% the maximum thermal stress which is appliedto the solder bump compared with that of the usual electronic component,though it can reduce less than that of the electronic component all ofwhose solder bumps are hourglass-shaped.

Third Exemplary Embodiment

A third exemplary embodiment of the present invention will be describedin the following. FIG. 9A shows a top view of a resin substrate of anelectronic component and FIG. 9B shows a top view of an LSI chip of thisembodiment. In FIG. 9A, an area on which an LSI chip 12B is mounted isindicated by a dotted line.

In FIG. 9A, a plurality of electrode pads 13B is arranged on the resinsubstrate 14B in an aligned state along a line 141 which is at angle θwith a line 142 parallel to an outer edge 140 of the resin substrate14B. Here, similarly to the second embodiment of the present invention,the angle θ is expressed as

θ=tan−1 (d/r)

where r is distance from center O to solder bump which is the farthestfrom the center O, and d is diameter of the electrode pad. In FIG. 9B, aplurality of electrode pads 11B is arranged on the LSI chip 12B in analigned state along a line which is parallel to an outer edge of the LSIchip 12B.

When an electronic component 10B of this embodiment is manufactured withthe resin substrate 14B and the LSI chip 12B, at first, creamy solder issupplied on each of the electrode pads 13B of the resin substrate 14B.Then, the LSI chip 12B is put over the resin substrate 14B so that theelectrode pads 11 are opposed to the electrode pads 13B respectively viathe solders. FIG. 10A shows a state that the LSI chip 12B is put overthe resin substrate 14B.

The solders are heated in this state. While the solders are melting, theLSI chip 12B rotates the angle θ centering on the center of the resinsubstrate 14B with a vacuum suction tool or the like. As shown in FIG.10B, when the LSI chip 12B and the resin substrate 14B rotate the angleθ relatively, each side of the resin substrate 14B and each side of theLSI chip 12B become parallel. Moreover, the solders are stretched in aslant direction as shown in FIG. 10 c.

The solders are cooled in this state and are solidified as the solderbumps 15B, so the electronic component 10B including thehourglass-shaped solder bumps 15B in which each side of the resinsubstrate 14B and each side of the LSI chip 128 become parallel ismanufactured.

In the above-mentioned manufacturing method of the electronic component10B, a precise lifting apparatus is unnecessary. While it is necessarythat the electrode pads 13B are arranged along a line which is at theangle θ with the outer edge of the resin substrate 14B, the electrodepads 11B and the electrode pads 13B can be formed with the same methodsince positions of the electrode pads 13B correspond to those of theelectrode pads 11B. Accordingly, a complicate process for manufacturingthe electrode pad is unnecessary.

In the electronic component 10C of this embodiment, a contact angle ofjoining area of the hourglass-shaped solder bump 15B is smaller thanthat of usual solder bump. Accordingly, stress which is applied to thejoining area of the hourglass-shaped solder bump 15B is reduced and itis consequently possible to suppress exfoliation of the joining area anddestruction of the solder bump 15B.

Moreover, in this embodiment, the shifting length between the electrodepads 11B and the electrode pads 13B which are arranged at the farthestposition from the center O is set to be nearly as long as diameters ofthe electrode pad 11B and the electrode pad 13B. Accordingly, it ispossible to maximally reduce the stress which is applied to the joiningarea of the solder bump 15B in a range where the solder bumps 158 arenot torn off.

Fourth Exemplary Embodiment

A fourth exemplary embodiment of the present invention will be describedin the following. FIG. 11A is a plan view of an electronic component 10Cand FIG. 11B is a side view thereof. In FIG. 11A, the electroniccomponent 10C includes an LSI chip 12C which has a plurality ofelectrode pads 11C, a resin substrate 14C which has a plurality ofelectrode pads 13C, and a plurality of solder bumps 15C each of whichjoins one of the electrode pads 11C and one of the electrode pads 13C.

In FIG. 11A and FIG. 11B, the electrode pads 11C and the electrode pads13C are arranged at positions which are slid parallel to the resinsubstrate 14C in one direction from their opposite positions.

When the electronic component 10C is manufactured, at first, creamysolder is supplied on each of the electrode pads 13C of the resinsubstrate 14C. The LSI chip 12C is put over the resin substrate 14C sothat the electrode pads 11C are opposed to the electrode pads 13Crespectively via the solders.

In this state, the LSI chip 12C and the resin substrate 14C start to beheated. While the solders are melting, the LSI chip 12C is slid in onedirection parallel to the resin substrate 14C. Here, this slid of theLSI chip 12C can be carried out by using a vacuum suction tool or byslanting the resin substrate 14C. Then, the solders are stretched in aslant direction shown in FIG. 11B. The solders are cooled in this stateand are solidified as the solder bumps 15C, so the electronic component10C including the hourglass-shaped solder bumps 15C is manufactured.

In the above-mentioned manufacturing method of the electronic component10C, a precise lifting apparatus is unnecessary. The electrode pads 11Cand the electrode pads 13C can be formed with the same method sincepositions of the electrode pads 13C correspond to those of the electrodepads 11C. Accordingly, a complicate process for manufacturing theelectrode pad is unnecessary.

Moreover, since only sliding the LSI chip 12C is carried out to deformthe solder bumps 15C, it is very easy to manufacture the electroniccomponent 10C.

In the electronic component 10C, a contact angle of joining area of thehourglass-shaped solder bump 15C is smaller than that of an usual solderbump. Accordingly, stress which is applied to the joining area isreduced and it is consequently possible to suppress exfoliation of thejoining area and destruction of the solder bump 15C.

Here, in this embodiment, the LSI chip 12C is slid by distance L in adirection which is indicated by an arrow Z in FIG. 1A. It is desirablethat the distance L, that is, sliding length between opposite theelectrode pads is shorter than diameters of the electrode pad 11 and theelectrode pad 13. When the distance L is nearly as long as diameters ofthe electrode pads 11C and the electrode pads 13C, it is possible tomaximally reduce the stress which is applied to the joining area of thesolder bump 15C in a range where the solder bumps 15C are not torn off.

In this embodiment, the LSI chip 12C is slid in one direction parallelto any side of the resin substrate 14C, however, the LSI chip 12C can beslid, for example, in a diagonal direction of the resin substrate 14C.

Fifth Fourth Exemplary Embodiment

A fifth exemplary embodiment of the present invention will be describedin the following. FIG. 12A is a plan view of an electronic component 10Dof this embodiment. FIG. 12B is a transverse cross-sectional view whichis taken along a line Y-Y′ of the electronic component 10D shown in FIG.12A. FIG. 12A and FIG. 12B are almost the same as FIG. 2A and FIG. 2Bdescribed in the second embodiment of the present invention. That is,each of electrode pads 11D of an LSI chip 12D and each of electrode pads13D of a resin substrate 14D are at positions which relatively rotatecentering on “O” from their opposite positions in FIG. 12A.

But manufacturing method of the electronic component 10D of thisembodiment is different from that of the electronic component 10 of thesecond embodiment. In the second embodiment, the LSI chip 12 is put overthe resin substrate 14 so that the electrode pads 11 of the LSI chip 12are opposed to the electrode pads 13 of a resin substrate 14respectively via the solders. Then, while the solders are melting, theLSI chip 12 rotates the angle θ in parallel to the resin substrate 14centering on “O”. When the solders are cooled in this rotated state andsolidify into hourglass-shaped, the electronic component 10 includingthe hourglass-shaped solder bumps 15 of the second embodiment ismanufactured.

In contrast, in the electronic component 10D of this embodiment, the LSIchip 12D with the electrode pads 11D is put over the resin substrate 14Dwith the electrode pad 13D so that each of each of the electrode pads11D and each of the electrode pads 13D are at positions which relativelyshifted from their opposite positions. In particular, each of theelectrode pads 11D and each of the electrode pads 13D are at positionswhich are relatively rotated at the angle θ centering on “O” shown inFIG. 12A from their opposite positions. Then, the solders start to beheated in the above state and the solders are melting, and each of thesolders slants toward nearby electrode pad 11D. Therefore, there is norotating operation of the LSI chip 12D during the heating process.Afterward, the solders are cooled and solidify into hourglass-shaped asthe solder bumps 15D. Then, the electronic component 10D including thehourglass-shaped solder bumps 15D is manufactured.

In the above-mentioned manufacturing method of the electronic component10D, neither a precise lifting apparatus nor a complicate process formanufacturing the electrode pad is unnecessary.

In the electronic component 10D, a contact angle of joining area of thehourglass-shaped solder bump 15D is smaller than that of an usual solderbump. Accordingly, stress which is applied to the joining area isreduced and it is consequently possible to suppress exfoliation of thejoining area and destruction of the solder bump 15D.

While the present invention has been described with above-mentionedembodiments, the present invention is not limited to each ofabove-mentioned embodiments. The present invention can include variousmodifications which a person skilled in the art can understand withregard to configuration and detail of the present invention. Moreover,the present invention can include an appropriate combination of parts orwholes of above-mentioned embodiments of the present invention.

In the electronic component 10, 10B, 10C and 10D according to the abovementioned exemplary embodiments, the maximum length of the shiftingbetween the first electrode pad 11, 11B, 11C and 11D and the secondelectrode pad 13, 13B, 13C and 13D which are corresponding is shorterthan a diameter each of the first electrode pad 11, 11B, 11C and 11D andthe second electrode pad 13, 13B, 13C and 13D.

In the electronic component 10, 10B and 10D according to the abovementioned exemplary embodiments, the first electrode pads 11, 11B and11D and the second electrode pads 13, 13B and 13D are at positions whichare rotated parallel to the second substrate 14, 14B and 14D centeringon a center of the first or second substrate from the oppositepositions.

In the electronic component 10C according to the above mentionedexemplary embodiments, the first electrode pads 11C and the secondelectrode pads 13C are at positions which are slid in one directionparallel to the second substrate 14C from the opposite positions.

In the electronic component 10, 10B, 10C and 10D according to the abovementioned exemplary embodiments, the first substrate 12, 12B, 12C and12D is a semiconductor chip and the second substrate 14, 14B, 14C and14D is a resin substrate.

In the method for manufacturing the electronic component 10, 10B and 10Caccording to the above mentioned exemplary embodiments, the maximumlength of the shifting between the first electrode pad 11, 11B and 11Cand the second electrode pad 13, 13B and 13C which are corresponding isshorter than a diameter each of the first electrode pad 11, 11B and 11Cand the second electrode pad 13, 13B and 13C.

In the method for manufacturing the electronic component 10, 10Baccording to the above mentioned exemplary embodiments, the firstsubstrate 12, 12B or the second substrate 14, 14B is shifted so that thefirst substrate 12, 12B rotates predetermined angle centering on centerof the first or second substrate from the opposite positions.

In the method for manufacturing the electronic component 10C accordingto the above mentioned exemplary embodiments, the first substrate 12C orthe second substrate 14C is shifted by sliding in one direction.

In the method for manufacturing the electronic component 10D accordingto the above mentioned exemplary embodiments, the maximum length of theshifting between the first electrode pad 11D and the second electrodepad 13D which are corresponding is shorter than a diameter each of thefirst electrode pad 11D and the second electrode pad 13D.

Here, when the related technology which is described in the backgroundart is applied to an electronic component which suppresses exfoliationof the joining area and destruction of the solder bump due to thethermal stress, the related technology has a following problem. That is,according to the related art 1, the LSI chip is lifted from the resinsubstrate when the solder bump melts. A precise lifting apparatus isneeded for lifting the LSI chip.

Moreover, according to the related art 2, a complex process is necessaryto manufacture the electrode pads, because it is necessary for theelectrode pads at the four corners of the LSI chip to be formed in adifferent manufacturing process from that of others.

On the other hand, when the electronic component of the presentinvention is applied to an electronic component which suppressesexfoliation of the joining area and destruction of the solder bump dueto the thermal stress, following advantages are made. That is, in theelectronic component of the present invention, a first substrate is putover a second substrate so that each of first electrode pads and each ofsecond electrode pads are at positions which are shifted from theiropposite positions and at least a part of solder bumps are solidifiedinto hourglass-shaped.

Accordingly, neither a complicate process for manufacturing theelectrode pads nor a precise lifting apparatus is necessary onmanufacturing the electronic component of the present invention.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, the invention is not limitedto these embodiments. It will be understood by those of ordinary skillin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the claims.

Further, it is the inventor's intention to retain all equivalents of theclaimed invention even if the claims are amended during prosecution.

1. A plurality of solder bumps which join together first electrode padsand second electrode pads at positions, which are shifted from oppositepositions where said first electrode pads opposite to said secondelectrode pads, wherein at least a part of said solder bumps aresolidified into hourglass-shaped.
 2. An electronic component,comprising: a plurality of first electrode pads arranged on a firstsubstrate; a plurality of second electrode pads arranged at positionscorresponding to said first electrode pads on a second substrate; and aplurality of solder bumps which join together said first electrode padsand said second electrode pads, wherein said first substrate is locatedover said second substrate so that said first electrode pads and saidsecond electrode pads are at positions which are shifted from oppositepositions where said first electrode pads opposite to said secondelectrode pads, and at least a part of said solder bumps are solidifiedinto hourglass-shaped.
 3. The electronic component according to claim 2,wherein the maximum length of said shifting between said first electrodepad and said second electrode pad which are corresponding is shorterthan a diameter each of said first electrode pad and said secondelectrode pad.
 4. The electronic component according to claim 2, whereinsaid first electrode pads and said second electrode pads are atpositions which are rotated parallel to said second substrate centeringon a center of said first or second substrate from said oppositepositions.
 5. The electronic component according to claim 2, whereinsaid first electrode pads and said second electrode pads are atpositions which are slid in one direction parallel to said secondsubstrate from said opposite positions.
 6. The electronic componentaccording to claim 2, wherein said first substrate is a semiconductorchip and said second substrate is a resin substrate.
 7. A method formanufacturing an electronic component, comprising: arranging a pluralityof first electrode pads and a plurality of second electrode pads on afirst substrate and a second substrate respectively so that positions ofsaid second electrode pads correspond to those of said first electrodepads; forming a plurality of solder bumps on said second electrode padsrespectively; putting said first substrate over said second substrate sothat said first electrode pads are respectively opposed to said secondelectrode pads via said solder bumps; shifting said first substrate orsaid second substrate in parallel to said second substrate while saidsolder bumps are melting so that said solder bumps are stretched in aslant direction to cause said solder bumps to be solidified intohourglass-shaped.
 8. The method for manufacturing the electroniccomponent according to claim 7, wherein the maximum length of saidshifting between said first electrode pad and said second electrode padwhich are corresponding is shorter than a diameter each of said firstelectrode pad and said second electrode pad.
 9. The method formanufacturing the electronic component according to claim 7, whereinsaid first substrate or said second substrate is shifted so that saidfirst substrate rotates predetermined angle centering on center of saidfirst or second substrate from their opposite positions.
 10. The methodfor manufacturing the electronic component according to claim 7, whereinsaid first substrate or said second substrate is shifted by sliding inone direction.
 11. A method for manufacturing an electronic component,comprising: arranging a plurality of first electrode pads and aplurality of second electrode pads on a first substrate and a secondsubstrate respectively so that positions of said second electrode padscorrespond to those of said first electrode pads; forming a plurality ofsolder bumps on said second electrode pads respectively; putting saidfirst substrate over said second substrate via said solder bumps so thateach of said first electrode pads and each of said second electrode padsare at positions which are shifted from their opposite positions tocause said solder bumps to be solidified into hourglass-shaped byheating.
 12. The method for manufacturing the electronic componentaccording to claim 11, wherein the maximum length of said shiftingbetween said first electrode pad and said second electrode pad which arecorresponding is shorter than a diameter each of said first electrodepad and said second electrode pad.